The present invention relates to corrosion inhibition in subterranean applications, and, more particularly, to corrosion inhibitor compositions comprising products of a reaction between aldehydes and amides and methods related thereto.
The corrosion of metal surfaces occurs when the metal surfaces are contacted by a corrosive environment containing an oxidizer (e.g., an electrochemical oxidizer, a chemical oxidizer or the like). Illustrative corrosive environments include, for example, acidic environments, environments containing water vapor in the presence of air and/or oxygen, and environments containing chloride or bromide ions, carbon dioxide and/or hydrogen sulfide. As used herein, the term “corrosion” refers to any reaction between a material and its environment that causes some deterioration of the material or its properties. Examples of common types of corrosion include, but are not limited to, the rusting of a metal, the dissolution of a metal in acids, and patina development on the surface of a metal.
Acidic environments can be produced by acidic treatment fluids that are commonly used in a number of operations in the oil and chemical industries. In such operations, any metal surfaces present are subjected to the corrosive environment of the treatment fluid. For example, metal surfaces (e.g., piping, tubular goods, heat exchangers and reactors) can be exposed to acidic treatment fluids in industrial chemical equipment. In subterranean applications, metal surfaces on various types of equipment are often exposed to corrosive conditions during downhole operations. For example, acidic treatment fluids are frequently utilized in the treatment of subterranean formations, and additional corrosive components including brine, carbon dioxide and/or hydrogen sulfide are commonly encountered downhole.
Acidic treatment fluids for downhole use include, for example, acidic clean-up fluids and stimulation fluids. Acidic stimulation fluids include, for example, treatment fluids used in hydraulic fracturing or matrix acidizing treatments. As used herein, the term “treatment fluid” refers to any fluid used in a subterranean application in conjunction with a desired function and/or for a desired purpose. The term “treatment fluid” does not imply any particular action by the fluid or any component thereof. Acidic treatment fluids can include a variety of acids such as, for example, hydrochloric acid, formic acid, hydrofluoric acid, and the like.
While acidic treatment fluids are useful for a variety of downhole operations, they can be somewhat problematic due to potential metal surface corrosion on downhole production tubing and tools, for which the repair or replacement costs are high. Furthermore, under typical downhole conditions, corrosion rates of metal surfaces are frequently increased due to elevated temperatures and pressures that are present in the subterranean environment. In addition to damage caused to downhole metal surfaces, corrosion can result in significant quantities of the acidic treatment fluid being neutralized, thereby reducing the treatment fluid's downhole effectiveness.
To combat potential corrosion problems, various corrosion inhibitors have been used to reduce or substantially prevent corrosion of metal and metal alloy surface on downhole equipment, all with varying levels of success. As used herein, the term “inhibit” and its derivatives refer to a lessening of the tendency of a phenomenon to occur and/or the degree to which that phenomenon occurs. The term “inhibit” does not imply any particular degree or amount of inhibition. Corrosion inhibitor compositions frequently include an aldehyde as the corrosion inhibiting component. A difficulty encountered with some common corrosion inhibitors is the limited temperature range over which they can function effectively. Another frequently encountered difficulty of common corrosion inhibitors is their unsatisfactory performance under highly acidic conditions. Under either or both of these conditions, an unacceptably high rate of corrosion can occur. Further, a number of common corrosion inhibitors have health, safety and/or environmental considerations that can geographically limit where they are able to be utilized. In the present invention, improved corrosion inhibitor compositions and various methods related thereto are described which address some of the foregoing considerations.